The CQ28 from SICK Inc., Minneapolis, MN, is a capacitive sensor in a thin, flat housing designed to detect liquids and bulk materials through nonmetallic walls at up to 10 mm. Features include teach-in functionality, mounting options, status LEDs, and PNP and NPN switching output versions. The LEDs show current switching state and quality of detection. The sensor also has enhanced electromagnetic compatibility to prevent spurious switching. Mounting options include clamp fitting, tie-wrap mounting, and recessed installation.